private void dataGridViewSach_Sach_CellClick(object sender, DataGridViewCellEventArgs e)
{
DataGridViewRow row = dataGridViewSach_Sach.CurrentRow;
if (!string.IsNullOrEmpty(row.Cells[0].Value.ToString()) && !string.IsNullOrEmpty(row.Cells[1].Value.ToString()))
{
textBoxMaSach_Sach.Text = row.Cells[0].Value.ToString();
textBoxMaDauSach_Sach.Text = row.Cells[1].Value.ToString();
textBoxTenSach_Sach.Text = row.Cells[2].Value.ToString();
checkBoxTinhTrang_Sach.Checked = (bool)row.Cells[3].Value;
sach_MaSach = Convert.ToInt32(row.Cells[0].Value);
dataGridViewDauSach_Sach.DataSource = dauSachBUS.DauSach_Sach(Convert.ToInt32(row.Cells[1].Value));
dataGridViewDauSach_Sach.Columns[0].HeaderText = "Mã Đầu Sách";
dataGridViewDauSach_Sach.Columns[1].HeaderText = "Tên Đầu Sách";
dataGridViewDauSach_Sach.Columns[2].HeaderText = "Mã Kệ Sách";
dataGridViewDauSach_Sach.Columns[3].HeaderText = "Số Lượng Hiện Tại";
dataGridViewDauSach_Sach.Columns[4].HeaderText = "Tổng Số";
}
}